1. Field of the Invention
The present invention relates generally to agricultural implements with a drawbar pivotally mounted on a frame by a bracket and bushing assembly.
2. Related Art
Implements such as a grain drill typically include an opener assembly having a pair of drawbars with forward apertured ends pivotally connected to a frame-mounted bracket and aft ends supporting a furrow-forming device such as a disk opener. Each of the forward ends of the drawbars is attached to the mounting bracket by a bolt that extends through the bracket and through a hard bushing; a washer and locknut secure the bushing against the side of the bracket and maintain the apertured end of the drawbar on the bushing.
During normal field-working operations, the pivotal area wears and loosens as high loads and vibration are encountered. The forward end of the drawbar often binds against the washer causing the washer to rotate on the bolt which in turn results in loosening of the nut. The bushings at times will rotate and friction between the bushing end and the bracket causes wear that results in more play in the connection. As the pivotal connections loosen with wear and nut rotation, the opener assemblies tend to wobble and vibrate and do not trail as well as they should.
Various methods, including the use of more expensive high grade bolts and higher tightening torques, have reduced the loosening problem somewhat. However, the nuts still loosen and the bushings wear prematurely, both axially with bushing rotation and circumferentially as the drawbars pivot.